Usando sed :
sed 'h;s/,.*/,/;s/ //g;G;s/\n//' data.csv
Explicado:
h - stash current line to the hold space
s/,.*/,/ - remove everything after the first comma
s/ //g - remove spaces
G - append the line from the hold space back to the pattern space
s/\n// - remove extra newline, as left by G